JDB shows inconsistent behaviour with JNI Based Programs.

Question

package com.RJCBEmulator;
public class Testing
     public static void main(String[] args) {
System.out.println("Start");
          NativeObject myClass = new NativeObject();
     System.out.println("Second line main" );
          myClass.printInfo();
public class NativeObject {
     static
          System.loadLibrary("RJCBEmulator");
     public NativeObject()
          nativeHandle = InitializeNative(1);
     public native long InitializeNative(int nClassId);
public void printInfo()
System.out.println( "Successful" );
     public long nativeHandle;
JNIEXPORT jlong JNICALL Java_com_RJCBEmulator_NativeObject_InitializeNative(JNIEnv *env, jobject obj, jint jnIID)
printf( "Inside InitializeNative\n");
jlong retVal;
switch( jnIID )
     case 1 :
     // do something
     break;
     case 2 :
     // do something
     break;
return 999;
when executed this program with java, I get this trace.
Start
Inside InitializeNative
Second line main
Successful
and when running the same program in jdb, I get the following trace
Start
Second line main
Successful
Inside InitializeNative
I am using jre1.4.1, I tried it with 1.3.1 and it works. Looks like JNI code is getting executed on a separate thread in JDB based on jre1.4.1.
Is there anybody who is facing this problem? Is there a workaround?

Answer 1

Start by testing your application using J2SE 1.4.1
(or the latest release available to you) and adding
"-Xcheck:jni" to the command line. This will perform
extra run-time checking on all JNI calls.
I don't
just want to see what native code parts that is
entered, I also want to be able to set breakpoints in
the native code (C code).There are debuggers that can work with both Java Language
and native code, but they need native support (in addition
to the Java Platform Debugger Architecture [JPDA]) to do it.
One example (on Solaris) is the latest release of dbx.
For more information, take a look at:
http://wwws.sun.com/software/sundev/suncc/documentation/mr/READMEs/dbx.html#new